1.在等腰△ABC中,AB=AC,點(diǎn)D,E是邊BC上的動(dòng)點(diǎn)(點(diǎn)D在點(diǎn)E的左側(cè)),連接AD、AE.
(1)如圖1,若∠ADC=60°,BD=2CE,求證:DE=AD+CE;
(2)如圖2,過(guò)點(diǎn)A作AM⊥BC于點(diǎn)M,將點(diǎn)E繞著點(diǎn)M旋轉(zhuǎn),點(diǎn)E的對(duì)應(yīng)點(diǎn)落在線段AM上的點(diǎn)N處,連接DN,若
,AN=MC,∠ADN=∠BAD+∠NDM,求證:AB=CD;
(3)如圖3,將△ABD沿AD翻折,使得點(diǎn)B落在點(diǎn)G處,點(diǎn)F是AC的中點(diǎn),連接EG、EF,若AB=5,
,在點(diǎn)D,E運(yùn)動(dòng)的過(guò)程中,當(dāng)四邊形ADEF的周長(zhǎng)取得最小值時(shí),請(qǐng)直接寫(xiě)出此時(shí)△AEG的面積.